In recent years, mobile terminal products such as mobile phones, tablet computers, and the like have developed rapidly. In addition to pursuit of extreme in hardware configuration, terminal manufacturers also pay more attention to user experience of mobile terminals.
In consideration of user experience of mobile terminals, the terminal manufactures require that a backlight source of a liquid crystal display module can be lighted up by a low current. In order to ensure that product brightness can bring a relatively soft visual experience to a user instead of dazzling the user when a mobile terminal product is used in a dark environment, the minimum brightness of the liquid crystal display module needs to be lower than a certain threshold (the threshold varies from manufacturer to manufacturer, for example, products of Apple Inc. are mostly required to have a minimum brightness smaller than 3˜5 cd/m2), which actually requires that the liquid crystal display module can ensure not only a display function but also a uniform display under a low current. The demand for low current driving capacity of the liquid crystal display module is actually the demand for low current driving capacity of the backlight source (e.g., backlight LED). Therefore, it is necessary to add a low current detection procedure for the backlight source in shipment and incoming detection of the backlight source, to ensure that the liquid crystal display module meets the demand of the terminal manufacturers.
However, currently, a common backlight source detection device cannot provide a current of 500 uA or even lower e.g., 150 uA˜200 uA); moreover, a detection device which can provide such a low current is relatively high in cost, and not convenient to move, carry, and apply in large quantities.